Abstract
A large number of Fusarium isolates was collected from blighted wheat spikes originating from 175 sampling sites, covering 15 provinces in China. Species and trichothecene chemotype determination by multilocus genotyping (MLGT) indicated that F. graminearum s. str. with the 15-acetyl deoxynivalenol (15ADON) chemotype and F. asiaticum with either the nivalenol (NIV) or the 3-acetyl deoxynivalenol (3ADON) chemotype were the dominant causal agents. Bayesian model-based clustering with allele data obtained with 12 variable number of tandem repeats (VNTR) markers, detected three genetic clusters that also show distinct chemotypes. High levels of population genetic differentiation and low levels of effective number of migrants were observed between these three clusters. Additional genotypic analyses revealed that F. graminearum s. str. and F. asiaticum are sympatric. In addition, composition analysis of these clusters indicated a biased gene flow from 3ADON to NIV producers in F. asiaticum. In phenotypic analyses, F. asiaticum that produce 3ADON revealed significant advantages over F. asiaticum that produce NIV in pathogenicity, growth rate, fecundity, conidial length, trichothecene accumulation and resistance to benzimidazole. These results suggest that natural selection drives the spread of a more vigorous, more toxigenic pathogen population which also shows higher levels of fungicide resistance.
Highlights
Fusarium head blight (FHB) or head scab is a devastating disease of wheat (Triticum aestivum L) and barley (Hordeum vulgare L)in China [1,2,3,4] and many other regions of the world [5,6]
We investigated the possibility of natural hybridization between F. graminearum s. str
We found an uneven distribution of F. graminearum s. str. and F
Summary
Fusarium head blight (FHB) or head scab is a devastating disease of wheat (Triticum aestivum L) and barley (Hordeum vulgare L)in China [1,2,3,4] and many other regions of the world [5,6]. Fusarium head blight (FHB) or head scab is a devastating disease of wheat (Triticum aestivum L) and barley (Hordeum vulgare L). FHB causes quantitative yield loss but may reduce grain quality due to contamination of mycotoxins produced by the Fusarium pathogens [7]. In China, wheat is an important crop, second in importance only to rice [10]. FHB has been a problem in some provinces and in some years since 1936, when the first serious outbreak occurred [10]. During the past ten years, epidemic outbreaks have become more frequent and severe in China. The disease frequently occurs in wheat growing areas in the middle and lower valleys of the Yangtze River and the mountainous areas in southwest China [3]. FHB has become an increasing problem characteristics between the four population clusters identified, which may contribute to differences in fitness or aggressiveness
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